In general, orthogonal frequency-division multiplexing (OFDM) is widely used in a digital audio broadcasting (DAB) receiver and a digital television; digital transmission technology of wireless local area network (WLAN), wireless asynchronous transfer mode (WATM), and so on.
Such OFDM makes a data column with a high transfer rate be divided into multiple data columns with a lower transfer rate, and multiple sub-carriers are employed to simultaneously transmit the data columns. Moreover, each of the sub-carriers keeps orthogonality to each other.
In OFDM, a reference signal is a signal for time or frequency synchronization, which is utilized as a criterion for data transmission of a pilot signal. Meanwhile, in the pilot signals, a pilot signal with a power larger than the information carrier of the data is called a boosted pilot signal (hereinafter referred to as boosted pilot signal). Such boosted pilot signal has a continual pilot signal (CP signal) used in a digital broadcasting signal of DVB-terrestrial (DVB-T), DVB-handheld (DVB-H), integrated services digital broadcasting-terrestrial (ISDB-T), etc. and a scattered pilot signal (SP signal).
The receiver, which uses this transmission criterion, utilizes the continual pilot signal and the scattered pilot signal to perform an integral frequency synchronization.
When a transmitter transmits data to the receiver, due to abnormal actions of the transmitter, or error actions which an I signal (time domain In-phase signal) and a Q signal (Quadrature phase signal) of the receiver having a phase difference of 90° therebetween are exchanged and then the receiver is coupled, a phenomenon of a spectrum inversion will occur.
However, under a condition that a receiver side employs the signal which occurs the spectrum inversion phenomenon to perform a signal processing such as a fast Fourier transform (FFT) and then a transmitter side repairs the transmitted data, a problem that normal data can not be output due to the repair of abnormal data will occur.
Therefore, in order to perform suitable signal processing according to whether the spectrum inversion phenomenon occurs after detecting the spectrum inversion phenomenon, the receiver side will detect whether the spectrum inversion phenomenon occurs.
One example for detecting the spectrum inversion phenomenon can utilize frequency axial differential correlation and the reference signal, such as a pseudo random binary sequence (PRBS) signal.